Homes and similar residential dwelling units have traditionally been constructed on-site. Moreover, residential dwelling units have typically been constructed on an individual unit basis, even in the case of construction projects wherein the individual homes are largely identical. These factors, plus delays caused by weather, unavailability of materials, etc. have combined to dramatically increase the cost of homes constructed in the conventional manner.
As opposed to the foregoing, mobile homes are almost universally constructed in factories. By means of automation, standardization, and other mass production techniques, the costs of manufacturing mobile homes has remainded relatively low. Thus, when compared on a per square foot basis, homes constructed by conventional techniques typically cost up to five times as much as mobile homes.
The relatively new concept of modular housing combines the best features of traditional construction and mobile home manufacturing to provide residential dwelling units which are economical to purchase and yet afford many of the amenities that have heretofore been unavailable at reasonable prices. Each home is constructed from one or more modules which are entirely constructed at a factory utilizing mass production techniques. This is advantageous not only from the standpoint of economy, but also because it facilitates the subsequent expansion of the home by simply adding more modules. The completed modules are transported from the factory to the homesite in the manner of a mobile home. At the site the modules are removed from the transportation apparatus and are installed on a permanent foundation. Walks and driveways, patios, decks, pools, hot tubs, and other amenities usually found only in expensive custom homes are then added to complete the construction of the modular home.
One factor that is heretofore added unnecessarily to the cost of modular housing involves the construction of the foundation at the homesite. Thus, traditional foundation construction techniques require a relatively large number of construction personnel to visit the homesite on at least two occasions. On the first trip the necessary excavation work is completed, forms are constructed, reinforcing structure is constructed within the forms, and the concrete is poured. On the second trip the forms are removed and the excavation is backfilled to the extent necessary. It will thus be understood that considerable costs savings can be realized by providing a foundation construction technique that does not require the construction personnel to make a return trip to the homesite simply for the purpose of removing the forms and backfilling the excavation. On the other hand, proper module housing construction requires the precise leveling and alignment of the individual modules at the time of installation on the permanent foundation. Thus, a need exists for a foundation system adapted for use in conjunction with module housing which is both economical and yet affords very accurate positioning of individual modular units.
The present invention relates to a foundation system for modular housing which fulfills the foregoing and other requirements to provide significant improvements over the prior art. In accordance with the broader aspects of the invention, the modules comprising a modular housing installation are supported on a series of pier columns. Each pier column is constructed by forming a bore hole in the earth, installing suitable reinforcing structure in the bore hole, and then filling the bore hole with concrete. Each pier column further comprises an outer support member embedded in the concrete and projecting upwardly therefrom and an inner support member telescopingly received in the outer support member.
In the installation of modular housing units, each module is positioned over the pier columns comprising the foundation system of the present invention utilizing the transportation apparatus. Jacks are employed to level and align each module. The inner support member of each pier column is then secured, both to the chassis of the module and to the outer support member. When the inner support members of all of the pier columns have been secured, the transportation apparatus and the jacks are removed, whereupon the installation of the module is complete. If desired, a suitable exterior wall may be constructed to give the installation a more completed appearance.
In accordance with more specific aspects of the invention, the outer and inner support members of each pier column preferably comprises steel tubes. Since steel beams are often employed as chassis components in the construction of modules for modular housing installations, the construction of the outer and inner support members of the pier columns from steel allows the connection of the inner support members both to the chassis of the module and to the outer support member by means of welding. Although other techniques may be used to secure the inner support members in place, the use of welding is preferred because it is rapid, economical and permanent in nature.